This course provides a detailed treatment of the transport of energy in micro- and nano-scale structures. The physical nature of energy transport by three carriers—electrons, phonons, and photons—is explored from first principles, as well as interactions among these carriers. Bulk material properties, such as thermal and electrical conductivity, are derived from statistical particle transport theories, and the effects of spatial confinement on these properties are quantified. Following the treatment of fundamental physical principles, the course focuses on contemporary engineering applications, such as interfacial heat transfer, heat generation and transport in semiconductor devices, quantum wells, wires, and dots, and direct energy conversion devices such as thermoelectrics. The applications are interdisciplinary in nature and do not presume prior expertise.